Select all vertices within box boundary when in Front view
The question was answered by the following comment:

It's not wireframe mode that lets you select backfacing vertices, it's X-ray mode. They are two separate modes. The one you want is the button with two interesting squares. Turn that on and you can select all vertices inside the rectangle. Also you can constrain your scale to X, Y or Z by typing &quot;SX&quot;, &quot;SY&quot; or &quot;SZ&quot; and inputting a number or moving the mouse and clicking. You can also omit axes from scaling: &quot;S+SHIFT+Z+2.5&quot; (no plusses) scales the object along the X and Y axes by a factor of 2.5 but ignores Z. Also note that you can change the orientation of these axes (global local normal, etc) – hatinacat2000 Jul 15 at 23:33